Spermatozoa cooled to 5°C one day after collection from porcine commercial semen doses retain sperm functionality with reduced bacterial load

Transmembrane protein 95 as a promising molecular marker of ram sperm functionality

The optimization of preservation protocols (refrigeration and freezing) in ovine species is necessary for a wider diffusion of artificial insemination in this species. Besides the ram sperm quality assays, the characterization of novel proteins could be crucial for improving these protocols employing biomarkers. The protein transmembrane 95 (TMEM95) is a sperm membrane protein associated with oocyte-sperm fusion previously described in bull or mouse. However, this protein has not yet been characterized in the ram until now. In this work, different experimental groups based on sperm functionality: capacitated, refrigerated at different times (5 °C 24 h, 5 °C 48 h, and 5 °C 72 h), and frozen-thawed sperm samples were analyzed and compared to initial sperm quality samples (15 °C 3 h) to characterize the expression of this novel protein and its relationship with other sperm quality markers (motility, kinetic parameters, viability, apoptosis-like events, mitochondrial function, acrosome-reacted, zinc content as marker of capacitation). In addition, capacitation status was tested by Fluozin-3, a novel fluorescent probe measuring zinc content used for the first time in ram sperm. After capacitation induction, as expected, acrosome reactive spermatozoa and zinc signature 2 and 3 were significantly increased, while linearity was significantly (P < 0.05) decreased compared to non-capacitated samples. Concerning TMEM95, its profile was significantly (P < 0.05) increased after the capacitation process, confirming its relationship with this spermatozoa status. Attending to preservation processes, as expected, semen quality decreased progressively during liquid storage, and a significant (P < 0.05) decrease was observed at 24 h according to fast progressive motility and linearity. TMEM95 profile showed the same decrease tendency, showing a significant reduction (P < 0.05) at 48 h with respect to the control samples. Finally, after the cryopreservation process, the semen quality of the thawed samples suffered a detrimental effect compared to the initial control sample, concerting all studied parameters accomplished by a significant (P < 0.05) decrease in TMEM95 profile compared to initial control samples. When we analyzed the TMEM95 correlation with other sperm quality markers, the highest positive correlations observed were with low sperm quality parameters in capacitated samples, such as apoptosis-like changes and acrosome-reaction. On the other hand, the highest positive correlations observed between TMEM95 and sperm quality parameters in preservation process samples were observed with suitable sperm quality parameters (motility, viability, and mitochondrial functionality). According to our results, this novel protein could be considered a predictor of early damage in ram sperm preservation protocols (cooling and freezing), considering its relationship with capacitation and membrane integrity status.

Contaminant toxicity of concern for boars and semen used in assisted reproduction programs

The commercial swine industry utilizes artificial insemination (AI) in their breeding programs. With this assisted reproductive technology, the process starts by obtaining fresh ejaculates from desirable boars who are housed in a dedicated facility (i.e., stud) that also contains a clean-room laboratory where semen quality is assessed and then ejaculates processed into AI doses. In concert with AI adoption, disruptions in sow herd reproductive performance have been traced back to contributions made from the boar stud. Through field investigations and research, several extrinsic contaminants have been identified that impact semen quality either at the boar or AI-dose level. These contaminants can be categorized as either biological or chemical in origin, eliciting reprotoxic outcomes at the boar level and/or spermatotoxicity at the AI-dose level. Biological contaminants include multiple genera of primarily opportunistic microbes (i.e., bacteria, fungi), along with their secondary metabolites (e.g., endotoxins, exotoxins, mycotoxins). Chemical contaminants appear to originate from products used at the stud, and include cleaning agent/disinfectant residues, leachates from gloves and plastics, semen extender impurities, purified and drinking water impurities, and pesticides (i.e., biocides, fungicides, herbicides, insecticides, wood preservatives). In conclusion, contaminants are a real and constant threat to the health and productivity of a stud, and have caused significant reproductive and economic losses in the swine industry. The knowledge gained in recognizing the types and sources of contaminants provides a solid foundation for the development and implementation of pro-active strategies that mitigate risk to the industry.

The future of equine semen analysis

We are currently experiencing a period of rapid advancement in various areas of science and technology. The integration of high throughput 'omics' techniques with advanced biostatistics, and the help of artificial intelligence, is significantly impacting our understanding of sperm biology. These advances will have an appreciable impact on the practice of reproductive medicine in horses. This article provides a brief overview of recent advances in the field of spermatology and how they are changing assessment of sperm quality. This article is written from the authors' perspective, using the stallion as a model. We aim to portray a brief overview of the changes occurring in the assessment of sperm motility and kinematics, advances in flow cytometry, implementation of 'omics' technologies, and the use of artificial intelligence/self-learning in data analysis. We also briefly discuss how some of the advances can be readily available to the practitioner, through the implementation of 'on-farm' devices and telemedicine.